This invention relates to a forward, reverse shifting device for a marine propulsion unit and more particularly to an improved shifting mechanism for such units.
Most well known marine outboard drives include an outer housing that is adapted to be mounted on the transom of a watercraft for steering movement about a generally vertically extending axis. Such outboard drives include a propulsion device contained within the lower unit, such as a propeller, and which is driven by a drive shaft that rotates about a generally vertically extending axis. For a wide variety of reasons, it is desirable to place the drive shaft axis as close as possible or even coincident with the steering shaft axis. By doing so, vibrations are reduced and steering is improved.
This type of drive, however, normally employs a forward, neutral, reverse transmission that consists of a driving bevel gear that is affixed to the lower end of the drive shaft and which drives a pair of counterrotating driven bevel gears that are journaled on the propeller shaft. A dog clutching sleeve, which is normally interposed between the driven bevel gears, is selectively movable to engage one or the other of the driven gears for rotation with the propeller shaft for driving it in the selected forward and reverse directions. The dog clutching sleeve is normally operated by means of some form of actuator which is in turn, controlled by a shift rod that extends vertically through the outer housing of the outboard drive unit. This shifting mechanism is normally located at the forward end of the propeller shaft and, accordingly, in order to accommodate this and also to permit it to pivot as a unit with the outboard drive when it is steered, the previous proposed constructions for effecting shifting have necessitated a rearward positioning of the drive shaft.
It is, therefore, a principal object of this invention to provide an improved shifting device for a marine propulsion unit which permits a forwardly positioned drive shaft.
It is a further object of this invention to provide an improved actuating mechanism for the shifting mechanism of a marine propulsion transmission which permits forward placement of the drive shaft without interfering with the operation of the shifting mechanism.